Method for inspecting droplet discharge head, device for inspecting droplet discharge head, and droplet discharge device

ABSTRACT

A method for inspecting a droplet discharge head includes generating illuminating light based on a color tone of a dot pattern of a droplet discharged from the droplet discharge head by selecting at least one of a plurality of illuminating light sources of different color tones and by modulating light illuminated from the at least one of the illuminating light sources based on the color tone of the dot pattern, capturing an image of the dot pattern while a photographed region including the dot pattern is being illuminated by the illuminating light, and inspecting the image of the dot pattern using image processing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No.2009-065724 filed on Mar. 18, 2009. The entire disclosure of JapanesePatent Application No. 2009-065724 is hereby incorporated herein byreference.

BACKGROUND

1. Technical Field

The present invention relates to a method for inspecting a dropletdischarge head, a device for inspecting a droplet discharge head, and adroplet discharge device.

2. Related Art

Electro-optic devices are currently being manufactured using inkjet-typedroplet discharge devices. Examples of electro-optic devices includeliquid crystal display devices, organic EL (electro luminescence)devices, and other devices that use color filters. When theseelectro-optic devices are manufactured using a droplet discharge device,droplets must be discharged (dripped) in a predetermined amount withextreme accuracy from a droplet discharge head to a predeterminedposition on a discharge target.

Japanese Laid-Open Patent Application No. 2005-14216 discloses aninvention of a method and device for inspecting a dot pattern ofdroplets discharged from a nozzle of a droplet discharge head. Theinvention of Japanese Laid-Open Patent Application No. 2005-14216 iswherein a plurality of dot patterns formed in alignment on an object tobe inspected is photographed and an electronic image acquired byphotographing is subjected to image processing, whereby the intervalsbetween adjacent dot patterns are measured and the measured values arecompared with a regular value, allowing positional misalignment of thedot patterns to be detected.

SUMMARY

When the dot patterns are photographed, an illumination device is usedto illuminate the photographed area in order to accurately acquireimages of the shapes of the dot patterns. White light, for example, isoften used as the illuminating light emitted by this illuminationdevice. Specifically, since white light is colorless (strictly speaking,is only slightly colored) and does not acquire a color tone in any ofthe color regions red (R), green (G), or blue (B), it is possible to usemonochromatic light to enhance the contrast between the object beinginspected (usually white paper) and each dot pattern of functionalliquid droplets containing red, green, and blue pigments used in themanufacture of color filters, for example.

However, color diversification has recently become common in dropletsdischarged from droplet discharge heads, and a problem occurs in thatthe shapes of the dot patterns cannot be accurately acquired throughimaging, depending on the color tone of the droplets. Dot patterns ofdroplets containing yellow, magenta, cyan, and other pigments havinglight, pale color tones represent a fitting example. This leads to casesin which sufficient contrast cannot be obtained by illumination withwhite light, adequate contrast cannot be obtained for electronic imagedespite the fact that dot patterns have been photographed, andinspection using image processing cannot be performed appropriately.

The present invention was devised in view of the problems describedabove, and an object thereof is to provide a method for inspecting adroplet discharge head, a device for inspecting a droplet dischargehead, and a droplet discharge device whereby dot patterns having apredetermined color tone can be appropriately inspected using imageprocessing.

In order to solve the problems described above, a method for inspectinga droplet discharge head according to a first aspect includes generatingilluminating light based on a color tone of a dot pattern of a dropletdischarged from the droplet discharge head by selecting at least one ofa plurality of illuminating light sources of different color tones andby modulating light illuminated from the at least one of theilluminating light sources based on the color tone of the dot pattern,capturing an image of the dot pattern while a photographed regionincluding the dot pattern is being illuminated by the illuminatinglight, and inspecting the image of the dot pattern using imageprocessing.

Using the method according to the first aspect makes it possible toselect the illuminating light source to be used based on the color toneof the photographed dot patterns, and to generate illuminating lightsuited to the color tone of the dot patterns by modulating the light ofthe illuminating light source. Therefore, the dot patterns of thephotographed target can be photographed with a high contrast.

In the method according to a second aspect, the generating of theilluminating light preferably includes selecting at least two of theilluminating light sources and combining lights from the at least two ofthe illuminating light sources to generate the illuminating light basedon the color tone of the dot pattern.

Using the method according to the second aspect makes it possible togenerate illuminating light suited to the color tone of the dot patternsby combining illuminating light of different color tones. Therefore,there is no need to provide an illuminating light source for each colortone, the number of illuminating light sources that need to be installedcan be reduced, costs can be curtailed, and space can be conserved.

In the method according to a third aspect, the generating of theilluminating light preferably includes selecting the at least one of theilluminating light sources including an illuminating light source of redlight, an illuminating light source of green light, and an illuminatinglight source of blue light.

Using the method according to the third aspect makes it possible togenerate illuminating light of various color tones by using light of thethree primary colors.

In the method according to a fourth aspect, the generating of theilluminating light preferably includes generating the illuminating lightin a color tone that is complementary to the color tone of the dotpattern.

By using the method according to the fourth aspect, illuminating lightis generated in a color that is complementary to the color tone of thedot patterns in the color circle, whereby the dot patterns of thephotographed target can be photographed with the highest possiblecontrast.

A device for inspecting a droplet discharge head according to a fifthaspect includes a plurality of illuminating light sources of differentcolor tones, an illuminating light generating device, an imaging deviceand an inspecting device. The illuminating light generating device isconfigured to generate illuminating light based on a color tone of a dotpattern of a droplet discharged from the droplet discharge head byselecting at least one of the illuminating light sources and bymodulating light illuminated from the at least one of the illuminatinglight sources based on the color tone of the dot pattern. The imagingdevice is configured and arranged to capture an image of the dot patternwhile a photographed region including the dot pattern is beingilluminated by the illuminating light. The inspecting device isconfigured to inspect the image of the dot pattern using imageprocessing.

Using the configuration according to the fifth aspect makes it possibleto select the illuminating light source to be used based on the colortone of the photographed dot patterns, and to generate illuminatinglight suited to the color tone of the dot patterns by modulating thelight of the illuminating light source. Therefore, the dot patterns ofthe photographed target can be photographed with a high contrast.

A droplet discharge device according to another aspect includes thedevice for inspecting a droplet discharge head as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of thisoriginal disclosure:

FIG. 1 is a schematic plan view of a droplet discharge device accordingto an embodiment of the present invention;

FIG. 2 is a schematic view of a functional liquid droplet discharge headaccording to an embodiment of the present invention as seen from theside of the nozzle surface;

FIG. 3 is a block diagram showing the control system of the dropletdischarge device according to an embodiment of the present invention;

FIG. 4 is a schematic plan view showing the inspection area of aninspection camera according to an embodiment of the present invention;

FIG. 5 is a schematic plan view showing the configuration of a dischargeinspection unit according to an embodiment of the present invention;

FIG. 6 is a view indicated by the arrow A in FIG. 5;

FIG. 7 is a schematic view showing the color circle; and

FIGS. 8( a)-8(c) is a drawing showing the images obtained when yellowdot patterns formed on an inspection roll paper in an embodiment of thepresent invention are illuminated with (a) white light, (b) blue light,and (c) red light.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following is a description, made with reference to the accompanyingdrawings, of an embodiment of a method for inspecting a dropletdischarge head, a device for inspecting a droplet discharge head, and adroplet discharge device having this device, all according to thepresent invention. The droplet discharge device of the presentembodiment is installed in a drawing system incorporated in amanufacturing line for electro-optic devices, wherein specialized ink, aluminescent resin liquid, or another functional liquid is introducedinto a droplet discharge head, and a film is formed on a substrate.

FIG. 1 is a schematic plan view of a droplet discharge device accordingto an embodiment of the present invention. FIG. 2 is a schematic view ofa functional liquid droplet discharge head as seen from the side of thenozzle surface. FIG. 3 is a block diagram showing the control system ofthe droplet discharge device. FIG. 4 is a schematic plan view showingthe inspection area of an inspection camera. FIG. 5 is a schematic sideview showing the configuration of the discharge inspection unit. FIG. 6is a view indicated by arrow A in FIG. 5.

A droplet discharge device 1 has a drawing device 2 having a pluralityof functional liquid droplet discharge heads (droplet discharge heads)17, a maintenance device 3 provided to the drawing device 2, and adischarge inspection unit (inspection device) 4 for performing dischargeinspection on the functional liquid droplet discharge heads 17, as shownin FIG. 1. The droplet discharge device 1 also has an operation panel 5for inputting various data, and a controller (illuminating lightgenerating device and inspecting device) 105 for collectivelycontrolling all components as shown in FIG. 3. In FIG. 1, only onefunctional liquid droplet discharge head 17 is shown for the sake ofsimplicity.

The droplet discharge device 1 is configured to perform, under thecontrol of the controller 105, a maintenance process for maintaining orrestoring the discharge function of the functional liquid dropletdischarge heads 17 by using the maintenance device 3, a functionalliquid droplet discharge head inspection process for inspecting the dotpattern of the functional liquid droplet discharge heads 17 by using thedischarge inspection unit 4, and an actual drawing process fordischarging and depositing functional liquid droplets onto a substrate W(workpiece for actual drawing) by using the drawing device 2.

The drawing device 2 has an XY movement mechanism 11 composed of anX-axis table 12 for moving the substrate W in an X-axis direction, and aY-axis table 13 for moving a carriage 14, which carries the functionalliquid droplet discharge heads 17, in a Y-axis direction orthogonal tothe X-axis direction.

The area of intersection between the trajectory of movement of thesubstrate W by the X-axis table 12 and the trajectory of movement of thecarriage 14 by the Y-axis table 13 is the drawing area where the actualdrawing process is performed. The area (to the right in the drawing)outside of the X-axis table 12 on the trajectory of movement of a headunit 15 by the Y-axis table 13 is a maintenance area. Part of themaintenance device 3 is disposed in this maintenance area. The area infront of the X-axis table 12 is a substrate loading/unloading area forloading and unloading the substrate W to and from the droplet dischargedevice 1.

The X-axis table 12 has a positioning table 21 for positioning thesubstrate W, and a drawing X-axis slider 22 for supporting thepositioning table 21 and sliding the positioning table in the X-axisdirection.

The positioning table 21 is equipped with a vacuum-suction table forpositioning the substrate W by vacuum suction, a substrate θ-axis tablefor finely adjusting the θ position of the substrate W, and othercomponents. The drawing X-axis slider 22 is driven by an X-axis motordriver 113 (see FIG. 3) constituting an X-axis direction drive system.

The Y-axis table 13 is designed to straddle the X-axis table 12 and issupported by left and right support rods (not shown) set up on thefloor. The Y-axis table has the carriage 14 is mounted with thefunctional liquid droplet discharge heads 17, and a drawing Y-axisslider 23 for supporting the carriage 14 and sliding the carriage in theY-axis direction.

The carriage 14 has a head θ-axis table 26 for holding the plurality offunctional liquid droplet discharge heads 17 and correcting theθ-position of the heads. In the present embodiment, there is only onecarriage 14, but any desired number of carriages can be used. Thedrawing Y-axis slider 23 is driven by a Y-axis motor driver 114 (seeFIG. 3) constituting a Y-axis direction drive system.

The droplet discharge device 1 of the present embodiment is capable ofdischarging functional liquid droplets of numerous color tones includingcyan (C), magenta (M), and yellow (Y) in addition to red (R), green (G),and blue (B); and is provided with a predetermined number of functionalliquid droplet discharge heads 17 in accordance with the color tones.

The functional liquid droplet discharge heads 17 are supplied with afunctional liquid from a functional liquid pack or the like (not shown),and the heads then discharge the functional liquid through an inkjetsystem (e.g., driven by a piezoelectric element), as shown in FIG. 2.The functional liquid droplet discharge heads 17 each have two nozzlerows 42 (nozzle rows 42 a, 42 b) formed in parallel to each other on anozzle surface 41.

The length of each nozzle row 42 is 1 inch (about 25.4 mm), for example,and each nozzle row 42 is configured with 180 nozzles 43 aligned at aregular pitch (about 140 μm). The distance between two nozzle rows 42 isabout 2.2 mm, for example.

In the internal flow channel structures of the heads, the amountsdischarged from the nozzles 43 placed at the ends are greater than theamounts discharged from the nozzles 43 placed in the center. Therefore,the ten nozzles 43 at the ends are designated as non-discharge nozzleswhile the 160 nozzles 43 in the center are designated as dischargenozzles, the functional liquid is discharged only from the dischargenozzles, and functional liquid is not discharged from the non-dischargenozzles.

Referring back to FIG. 1, the droplet discharge device 1 has analignment device 16. The alignment device 16 has a substrate recognitioncamera 51 (see FIG. 3) for imaging and recognizing alignment marks (notshown) for the substrate W, and a head recognition camera 52 (see FIGS.1 and 3) for imaging and recognizing alignment marks (not shown) for thefunctional liquid droplet discharge heads 17.

In the maintenance area, the maintenance device 3 has a suction unit 56for suctioning the functional liquid from the nozzles 43 of thefunctional liquid droplet discharge heads 17, a wiping unit (not shown)for wiping down the nozzle surface 41 of the functional liquid dropletdischarge heads 17, a splatter monitoring unit (not shown) formonitoring the splattering of the functional liquid droplets, and othercomponents.

The discharge inspection unit 4 has a drawn unit 61 whereby inspectionroll paper (workpiece being inspected) S provided with a dot-pattern rowL (see FIG. 4) designed for inspection and created by the functionalliquid droplet discharge heads 17 is pulled out in the Y-axis direction,and an inspection photographing unit 62 for photographing thedot-pattern row L.

The discharge inspection unit 4 creates an image and recognizes thedrawn result of the dot-pattern row L formed by the functional liquiddroplet discharge heads 17, and inspects whether or not the functionalliquid droplets have been properly discharged from the nozzles 43.

The drawn unit 61 has an inspection X-axis slider 63 for moving theinspection roll paper S in the X-axis direction, and a winding mechanism(not shown) for winding up the inspection roll paper S.

The inspection X-axis slider 63 is provided independently of the drawingX-axis slider 22 and is driven by an inspection X-axis motor driver 113A(see FIG. 3) constituting an X-axis direction drive system. In thepresent embodiment, the drawn unit 61 and the positioning table 21 aremounted on separate X-axis sliders, but they may also be mounted on thesame X-axis slider.

The winding mechanism is configured to cause the undrawn area to facethe nozzle surface 41 of the functional liquid droplet discharge heads17 by winding up a predetermined length (e.g., 50 m) of the inspectionroll paper S in the Y-axis direction. This winding is performed witheach functional liquid droplet discharge head inspection process, forexample.

The inspection roll paper S is white inspection paper wound up into theshape of a roll, and has a base material layer and a receiving layerthat is formed (coated) over the surface of the base material layer andcan be penetrated by functional liquid droplets.

The inspection roll paper S has a width (e.g., 100 mm) corresponding toa plurality of inspection drawings. The inspection roll paper S also hasa predetermined length (e.g., 50 m) intended to reduce the frequency ofreplacing paper.

The workpiece designed for inspection and subject to the discharge ofthe functional liquid droplet discharge heads 17 is not limited to theinspection roll paper S, and may also be a strip of inspection paper,for example. The frequency of replacing paper can be reduced, however,by using a roll of inspection paper. Furthermore, although it requires acleaning process, a glass substrate can be used.

The inspection photographing unit 62 has an inspection camera 66(imaging device) for capturing an image of a dot pattern L (drawingresult) drawn on the inspection roll paper S, and an inspection Y-axisslider 67 for moving the inspection camera 66 in the Y-axis direction.

The inspection camera 66 has predetermined inspection regions R(photographed regions) as shown in FIG. 4. The inspection camera 66 is ahigh-resolution (narrow-viewing-angle) CCD (charge-coupled-device)camera, and is configured to be capable of producing photographs thatcontain a plurality of dot-pattern rows L.

The inspection Y-axis slider 67 is provided independently of the drawingY-axis slider 23 and is driven by an inspection Y-axis motor driver 114A(see FIG. 3) constituting a Y-axis direction drive system.

The discharge inspection unit 4 of the present embodiment is configuredto move the inspection regions R of the inspection camera 66 in thedirection of alignment of the dot-pattern rows L (in the Y-axisdirection in FIG. 4) to acquire a plurality of images, and to inspectthe dot-pattern rows L while connecting the images.

Specifically, when functional liquid droplets are discharged in a singlecycle from the nozzle rows 42 of the functional liquid droplet dischargeheads 17 to form dot-pattern rows L on the inspection roll paper S, asingle dot-pattern row L contains 160 dot patterns P (P1 to P160).Twenty-one dot patterns P are photographed for each image, and theimages are connected so that the twenty-first (final) dot pattern P21 ofthese patterns is also the first dot pattern P of the next image.Specifically, 20 (dots)×8 (images)=160 (dots), and one dot-pattern row Lcan be inspected with a total of eight images. For the inspection,predetermined inspection values based on the shape of the dot patterns Pare sequentially acquired and inspected using image processing. Theseinspection values include the surface area of the dot patterns P, thebarycentric position (coordinate position), and other values.

The inspection camera 66 has an illumination device 65 mounted aroundthe distal end of a high-power lens 66 a and used to emit illuminatinglight onto an inspection region R, as shown in FIG. 5.

The illumination device 65 has a red LED (Light Emitting Diode(illuminating light source)) 68R, a green LED (illuminating lightsource) 68G, and a blue LED (illuminating light source) 68B. Theillumination device 65 has an LED power source 69R for supplyingelectricity to the red LED 68R, an LED power source 69G for supplyingelectricity to the green LED 68G, and an LED light source 69B forsupplying electricity to the blue LED 68B. The LED light sources 69R,69G, and 69B are all driven under the control of the controller 105. Forexample, the illumination device 65 has a configuration in which thecontroller 105 can adjust the luminosity of the illuminating light,combine the illuminating light beams, emit an electronic flash, andperform other functions.

Light-emitting parts 70 of the illumination device 65 shown in FIG. 6are connected with the red LED 68R, the green LED 68G, and the blue LED68B via an optic fiber 71R, an optic fiber 71G, and an optic fiber 71B.Illuminating light, modulated after being selected from the red LED 68R,the green LED 68G, and the blue LED 68B, is emitted onto the inspectionregion R from the light-emitting parts 70 under the control of thecontroller 105. The light-emitting parts 70 are provided atpredetermined intervals in the periphery of the high-power lens 66 a,and are configured to be capable of uniformly illuminating theinspection region R. The light-emitting parts 70 may be configured toemit light of only a predetermined LED, and they may also be configuredto combine and emit light from a plurality of LEDs.

Next, the control system of the entire droplet discharge device 1 willbe described with reference to FIG. 3. The control system of the dropletdischarge device 1 essentially has an input unit 101 having theoperation panel 5 for inputting various data; an image recognition unit102 having various cameras provided to the alignment device 16 and thedischarge inspection unit 4; a drive unit 104 having various drivers fordriving the functional liquid droplet discharge heads 17, the XYmovement mechanism 11, and other components; and the controller 105 forcollectively controlling the droplet discharge device 1, including thesecomponents.

The drive unit 104 has a head driver 111 for controlling the dischargedriving of the functional liquid droplet discharge heads 17, and a motordriver 112 for drivably controlling the motors of the XY movementmechanism 11 and other components. The head driver 111 generates andapplies a predetermined drive waveform in accordance with an instructionfrom the controller 105, and controls the discharge driving of thefunctional liquid droplet discharge heads 17. The motor driver 112 hasthe X-axis motor driver 113, the Y-axis motor driver 114, a substrateθ-axis motor driver 115, a head θ-axis motor driver 116, the inspectionX-axis motor driver 113A, and the inspection Y-axis motor driver 114A.These drivers drivably control the drive motors of the X-axis table 12,the Y-axis table 13, the substrate θ-axis table, the head θ-axis table26, the inspection X-axis slider 63, and the inspection Y-axis slider 67in accordance with instructions from the controller 105.

The controller 105 has a CPU 121, a ROM 122, a RAM 123, and a P-CON 124,which are all connected to each other via a bus 125. The ROM 122 has acontrol program region for storing control programs and the likeprocessed by the CPU 121, and a control data region for storing controldata and the like for performing the actual drawing process and imagerecognition.

In addition to various register groups, the RAM 123 has a drawing dataregion for performing the actual drawing process, a discharge inspectiondata region for performing the functional liquid droplet discharge headinspection process, an image data region for temporarily storing imagedata, and other regions; which are used as various operating regions forthe control process.

The P-CON 124 is configured with a logic circuit for supplementing thefunction of the CPU 121 and handling interface signals with theperipheral circuitry. Therefore, the P-CON 124 introduces image data,various instructions from the input unit 101, or the like into the bus125 either directly or after processing, and, operating in cooperationwith the CPU 121, outputs data or control signals inputted to the bus125 from the CPU 121 or the like to the drive unit 104 either directlyor after processing.

After inputting various detection signals, various instructions, variousdata, and the like via the P-CON 124 in accordance with a controlprogram in the ROM 122 and processing the various data and the like inthe RAM 123, the CPU 121 controls the entire droplet discharge device 1by outputting various control signals to the drive unit 104 and othercomponents via the P-CON 124.

For example, the CPU 121 controls the functional liquid dropletdischarge heads 17, the X-axis table 12, and the Y-axis table 13 to drawpatterns on the substrate W under predetermined droplet dischargeconditions and predetermined movement conditions.

A simple description is given herein of a series of actual drawingprocesses performed on the substrate W by the droplet discharge device1. First, the substrate W is set on the positioning table 21 which hasbeen moved to the substrate loading/unloading area, and a substratealignment process is performed based on the results provided by thesubstrate recognition camera 51 in recognizing the image of substratealignment as a preparation prior to the discharge of functional liquiddroplets.

The functional liquid droplets are discharged while the functionalliquid droplet discharge heads 17 are moved relative to the substrate W.Specifically, main scanning, in which functional liquid droplets aredischarged and deposited from the plurality of functional liquid dropletdischarge heads 17 onto the substrate W while the substrate W is movedin the X-axis direction by the X-axis table 12, and sub scanning, inwhich the head unit 15 is moved in the Y-axis direction by the Y-axistable 13, are performed repeatedly, and functional liquid droplets aredischarged (drawn) over the entire substrate W.

The following is a detailed description, made with reference to FIGS. 7and 8, of the functional liquid droplet discharge head inspectionprocess (method for inspecting the functional liquid droplet dischargeheads) of the discharge inspection unit 4.

FIG. 7 is a schematic view showing the color circle. FIGS. 8( a)-8(c)are drawings showing the images obtained when yellow dot patterns Pformed on an inspection roll paper S are illuminated with (a) whitelight, (b) blue light, and (c) red light. The following descriptionpresents an example of a functional liquid droplet discharge headinspection process performed on functional liquid droplet dischargeheads 17 for discharging functional liquid droplets containing a yellowpigment.

The functional liquid droplet discharge head inspection process isperformed before and after the actual drawing process described above,wherein the discharge state of the nozzles 43 of the functional liquiddroplet discharge heads 17 is inspected. In cases in which no deviationsfrom normal operation are confirmed in the nozzles 43 by the functionalliquid droplet discharge head inspection process, the next actualdrawing process is then performed; and in cases in which a deviationfrom normal operation is confirmed, a maintenance process is performedon the functional liquid droplet discharge heads 17 before the nextactual drawing process is performed.

In the present process, the controller 105 first causes the functionalliquid droplet discharge heads 17 and the inspection roll paper S toface each other. The controller 105 then causes functional liquiddroplets to be discharged onto the inspection roll paper S from thenozzle rows 42, forming dot patterns P for inspection.

Next, in the present process, the controller 105 produces a contrastbetween the dot patterns P for inspection and the inspection roll paperS, and generates, based on the color tone of the dot patterns P,illuminating light capable of appropriately performing subsequent imageprocessing (illuminating light generation step).

In the present embodiment, the controller 105 selects the color tone ofthe contrast-enhancing illuminating light based on the color tone of thedot patterns P of the inspected target and data on the color wheel shownin FIG. 7. The color blue is selected here as a color that iscomplementary (opposite) to yellow on the color wheel in order tophotograph the dot patterns P with the highest possible contrast.

Next, the controller 105 selects the blue LED 68B from among theplurality of LEDs in order to generate the selected color. Specifically,the controller 105 causes only the LED light source 69B shown in FIG. 5to be driven. When the LED power source 69B is driven, the blue LED 68Bemits light, and the blue light is guided to the light-emitting parts 70via the optic fiber 71B. The blue illuminating light emitted from thelight-emitting parts 70 illuminates the inspection region R in a uniformmanner.

The controller 105 moves the inspection camera 66 mounted with theillumination device 65 for emitting blue light, and acquires an image ofthe inspection region R that includes the leftmost end dot pattern P ofthe dot pattern row L. Under the control of the controller 105, thedischarge inspection unit 4 uses image processing to acquire the surfaceareas of the dot patterns P, the barycentric positions (coordinatepositions), and other inspection values in a sequence that starts withthe dot pattern P position at one end (the leftmost end) of thedot-pattern row L.

After the image has been inspected, the controller 105 causes theinspection camera 66 to make a transition and acquire an image of thenext inspection region R, and connects both images based on thecoordinates of the dot pattern P (e.g., the dot pattern P21) for imageconnection. The dot pattern P at the rightmost end of the dot patternrow L is then inspected.

In the image acquired in the process described above, the contrastbetween the yellow dot patterns P and the inspection roll paper Silluminated with blue light is clearly manifested, as shown in FIG. 8(b). It is therefore possible to create an image of the dot patterns P byimage recognition, and the dot patterns P can be accurately inspected.

FIG. 8( a) shows the acquired image when white light is used, but thecontrast in the yellow dot patterns P is not clearly manifested withwhite light, and the contours of the dot patterns P are light in colorand blurred. An image process cannot be appropriately performed in thiscase.

FIG. 8( c) shows an acquired image when red light is used, but sinceyellow and red are in adjacent regions on the color wheel, contrast isnot manifested in yellow dot patterns P with red light, and the dotpatterns P disappear from the acquired image. The image processing isnot possible in this case.

In cases in which the dot patterns P have a color tone other thanyellow, the controller 105 uses data on the color wheel shown in FIG. 7,and causes the illumination device 65 to emit light of the optimum colortone in each case.

For example, when the dot patterns P have a cyan color tone, the red LED68R is selected and red illuminating light is emitted. When the dotpatterns P have a magenta color tone, the green LED 68G is selected andgreen illuminating light is emitted.

When the dot patterns P have a red color tone, for example, the greenLED 68G and the blue LED 68B are selected to create cyan, and compositelight of that color is emitted. When the dot patterns P have a greencolor tone, the red LED 68R and the blue LED 68B are selected to createmagenta, and composite light of that color is emitted. When the dotpatterns P have a blue color tone, the red LED 68R and the green LED 68Gare selected to create yellow, and composite light of that color isomitted.

The controller 105 adjusts, in accordance with the color tone of the dotpatterns P, the specifications (luminosity and the like) of the lightemitted by the illumination device 65. Green light is optimal in casesin which the controller 105 photographs magenta dot patterns P, forexample, but when the absolute value of the brightness is low, thecontroller performs a process such as extending the lighted time of theelectronic flash and increasing the luminosity.

Therefore, according to the present embodiment as described above, thereis provided a discharge inspection unit 4 which has an inspection camera66 for photographing dot patterns P of functional liquid droplets havinga predetermined color tone discharged from the nozzles 43 of functionalliquid droplet discharge heads 17, and an illumination device 65 foremitting illuminating light onto inspection regions R, and which usesimage processing to inspect the photographed dot patterns P; wherein theillumination device 65 has a red LED 68R, a green LED 68G, and a blueLED 68B as illuminating light sources of mutually different color tones,and the illumination device 65 uses a configuration having a controller105 for selecting at least one of the illuminating light sources basedon the color tone of the dot patterns P, and modulating the light of theselected illuminating light sources to generate the aforementionedilluminating light, whereby illuminating light suited to the color toneof the dot patterns P can be generated. Therefore, the dot patterns P ofthe photographed target can be photographed with a high contrast.

Therefore, in the present embodiment, dot patterns P having apredetermined color tone can be appropriately inspected using imageprocessing.

The preferred embodiment of the present invention was described abovewith reference to the drawings, but the present invention is not limitedto this embodiment. The shapes, combinations, and other features of thestructural components portrayed in the embodiment described aboverepresent but one example, and various modifications can be made basedon the design requirements and the like within a range that does notdeviate from the scope of the invention.

For example, in the embodiment described above, the illumination devicewas described as having illuminating light sources including a red LED,a green LED, and a blue LED, but the present invention is not limited tothis configuration alone.

For example, a device obtained by affixing having a color film of apredetermined color tone to a white electric lamp, a white LED, or thelike may be used instead. However, since illumination via a color filmis low in luminosity, more electricity is needed than in the embodimentdescribed above in order to increase the contrast. This is anotherreason why it is preferable in terms of energy conservation to used LEDscorresponding to each color as described above.

For example, in the embodiment described above, the dot-pattern row andthe next inspection region are photographed by an inspection camera, butthe inspection photographing unit may be provided with a drawingobservation camera having a high resolution and a narrow viewing angle,and a region camera having a low resolution and a wide viewing angle,and dot-pattern rows may be photographed by the drawing observationcamera while inspection regions may be photographed by the regioncamera.

The present invention can also be applied, for example, to a dropletdischarge device for spraying droplets (a liquid substance) in whichelectrode materials, color materials, and other materials used in themanufacture of liquid crystal displays, EL (electroluminescence)displays, and surface-emitting displays (FEDs) have been dispersed(dissolved) in a predetermined dispersion medium (solvent).

The droplet discharge device may also be a droplet discharge device forspraying a bioorganic substance used in the manufacture of biochips, ora droplet discharge device used as a precision pipette with whichdroplets are sprayed as specimens.

Furthermore, the device may be a droplet discharge device for sprayinglubricating oil on a clock, a camera, or another precision mechanism inpinpoint fashion; a droplet discharge device for spraying an ultravioletcuring resin or another transparent resin liquid onto a substrate inorder to form a miniature semispherical lens (optical lens) used in anoptical communication element or the like; a droplet discharge devicefor spraying an acid, an alkali, or another etching liquid in order toetch a substrate or the like; a fluid-spraying device for spraying agel; or a toner jet recording device for spraying a solid substance, anexample of which could be a toner or another powder. The presentinvention can be applied to any one of these types of droplet dischargedevices.

GENERAL INTERPRETATION OF TERMS

In understanding the scope of the present invention, the term“comprising” and its derivatives, as used herein, are intended to beopen ended terms that specify the presence of the stated features,elements, components, groups, integers, and/or steps, but do not excludethe presence of other unstated features, elements, components, groups,integers and/or steps. The foregoing also applies to words havingsimilar meanings such as the terms, “including”, “having” and theirderivatives. Also, the terms “part,” “section,” “portion,” “member” or“element” when used in the singular can have the dual meaning of asingle part or a plurality of parts. Finally, terms of degree such as“substantially”, “about” and “approximately” as used herein mean areasonable amount of deviation of the modified term such that the endresult is not significantly changed. For example, these terms can beconstrued as including a deviation of at least ±5% of the modified termif this deviation would not negate the meaning of the word it modifies.

While only selected embodiments have been chosen to illustrate thepresent invention, it will be apparent to those skilled in the art fromthis disclosure that various changes and modifications can be madeherein without departing from the scope of the invention as defined inthe appended claims. Furthermore, the foregoing descriptions of theembodiments according to the present invention are provided forillustration only, and not for the purpose of limiting the invention asdefined by the appended claims and their equivalents.

1. A method for inspecting a droplet discharge head comprising:generating illuminating light based on a color tone of a dot pattern ofa droplet discharged from the droplet discharge head by selecting atleast two of a plurality of illuminating light sources of differentcolor tones, by combining lights from the at least two of theilluminating light sources, and by modulating the lights illuminatedfrom the at least two of the illuminating light sources based on thecolor tone of the dot pattern; capturing an image of the dot patternwhile a photographed region including the dot pattern is beingilluminated by the illuminating light; and inspecting the image of thedot pattern using image processing.
 2. The method for inspecting adroplet discharge head according to claim 1, wherein the generating ofthe illuminating light includes selecting the at least one of theilluminating light sources including an illuminating light source of redlight, an illuminating light source of green light, and an illuminatinglight source of blue light.
 3. The method for inspecting a dropletdischarge head according to claim 1, wherein the generating of theilluminating light includes generating the illuminating light in a colortone that is complementary to the color tone of the dot pattern.
 4. Adevice for inspecting a droplet discharge head comprising: a pluralityof illuminating light sources of different color tones; an illuminatinglight generating device configured to generate illuminating light basedon a color tone of a dot pattern of a droplet discharged from thedroplet discharge head by selecting at least two of the illuminatinglight sources, by combining lights from the at least two of theilluminating light sources, and by modulating the lights illuminatedfrom the at least two of the illuminating light sources based on thecolor tone of the dot pattern; an imaging device configured and arrangedto capture an image of the dot pattern while a photographed regionincluding the dot pattern is being illuminated by the illuminatinglight; and an inspecting device configured to inspect the image of thedot pattern using image processing.
 5. The device for inspecting adroplet discharge head according to claim 4, wherein the illuminatinglight sources include an illuminating light source of red light, anilluminating light source of green light, and an illuminating lightsource of blue light.
 6. The device for inspecting a droplet dischargehead according claim 4, wherein the illuminating light generating deviceis configured to generate the illuminating light in a color tone that iscomplementary to the color tone of the dot pattern.
 7. A dropletdischarge device including the device for inspecting the dropletdischarge head according to claim 4.